class_docstr: Proportional Prioritized Experience Replay.
      
class_docstr_tok: ["Proportional","Prioritized","Experience","Replay","."]
code: def sample_one(self):
      assert self.elements.full(), "The replay memory is not full!"
      sample_val = np.random.uniform(0, self.elements.total_p)
      item, tree_idx, _ = self.elements.retrieve(sample_val)
      return item, tree_idx
  
file_path: PARL/benchmark/fluid/Prioritized_DQN/proportional_per.py
imports: import numpy
label_desc: Use image node_id 5 for calling the ProportionalPER obj's underlying member method code with example usage: obj.sample_one() and returns: item,  tree_idx